钢-混结合梁桥主梁顶升施工时双柱式花瓶桥墩空间受力分析

Spatial Stress Analysis of Double-column Vase Pier During Jacking Construction of Main Beam of Steel-concrete Composite Beam Bridge

借助某工程钢-混结合梁桥在主梁顶升施工过程中墩顶出现的裂缝现象,通过空间有限元程序Midas FEA建立实体单元对桥墩进行受力分析,验证该结构的安全性,通过成桥状态和顶升状态两种工况分析桥墩的受力变化并作对比。再根据花瓶墩顶“D区”类似“深梁”的受力特点,用实体计算所得的应力迹线绘制杆件,模拟规范中的拉压杆模型,采用规范中的拉压杆模型进行试验算,得出拉压杆模型并不适用于该类型桥墩系杆力计算的结论,同时为受力复杂的该类型桥墩结构提供了一种计算方法以供参考。明确了该顶升措施的利与弊,提醒为应对主梁特定的施工工艺而加强构件局部配筋设计。同时依据分析结果对施工中出现的裂缝问题采取适当的措施进行修复。

With the help of the cracks on the pier top of a steel-concrete composite beam bridge during the main beam jacking construction,the solid element is established by the spatial finite element program Midas FEA to analyze the stress of the pier,and the safety of the structure is verified.The stress change of the pier is analyzed through two working conditions of bridge completion state and jacking state.Then according to the stress characteristics of“D area”on the top of vase pier similar to“deep beam”,the bar is drawn with the stress trace obtained by solid calculation,and the tension and compression bar model in the code is simulated.The strut-and-tie model in the specification is used for trial calculation,and the test results show that the strut-and-tie model in the specification is not suitable for the calculation of the tie force of this type of bridge pier.In addition,the paper provides a calculation method for this type of complicated pier structure for reference.The advantages and disadvantages of this jacking measure are clarified,and the design of local reinforcement of components should be strengthened to deal with the specific construction technology of main beam.At the same time,according to the analysis results,appropriate measures are taken to repair the cracks in the construction.